1. Field of the Invention
The present invention relates to a process for the preparation of high molecular weight polyesters by reaction of an aromatic dicarboxylic acid with a mixture of alkane- and alkenediols in the presence of a catalyst, and in the substantial absence of oxygen.
2. Discussion of the Background
High molecular weight polyesters are materials having specific properties which are useful as a raw material for producing industrial high-quality, heavy-duty products. Frequently in the production of industrial high-quality products, relatively small amounts of a polyester with an exactly predetermined high molecular weight are demanded.
Since large amounts of polyesters of uniform molecular weight are conventionally produced by either large scale industrial continuous or batch-wise processes, it is usually uneconomical and industrially difficult to provide smaller partial amounts having a high specified molecular weight.
Some polyesters of high molecular weight are known in the prior art. They contain, inter alia, residues of unsaturated monomer components which are cross-linked, if appropriate, with compounds which are unstable to heat (see DE-AS 2 509 726; 2 509 790; and 2 552 424). One characteristic of these known high MW polyesters is that the final molecular weight must be specified prior to their preparation. Manipulation of the molecular weight subsequent to production is impossible or leads to a decrease in the properties of the product.
Thus, a method is needed which allows the preparation of high MW polyester in small amounts at specified molecular weights.